Android: Consolidate and simplify VSync logic

content/browser/renderer_host/render_widget_host_view_android.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/render_widget_host_view_android.h"
 
 #include <android/bitmap.h>
 
 #include "base/android/sys_utils.h"
 #include "base/basictypes.h"
@@ skipping 513 matching lines @@
   const float device_scale_factor = content_view_core_->GetDpiScale();
   if (overscroll_effect_->OnOverscrolled(
           content_view_core_->GetLayer(),
           base::TimeTicks::Now(),
           gfx::ScaleVector2d(params.accumulated_overscroll,
                              device_scale_factor),
           gfx::ScaleVector2d(params.latest_overscroll_delta,
                              device_scale_factor),
           gfx::ScaleVector2d(params.current_fling_velocity,
                              device_scale_factor))) {
-    content_view_core_->SetNeedsAnimate();
+    SetNeedsAnimate();
   }
 }
 
-void RenderWidgetHostViewAndroid::SendBeginFrame(
-    const cc::BeginFrameArgs& args) {
-  TRACE_EVENT0("cc", "RenderWidgetHostViewAndroid::SendBeginFrame");
-  if (!host_)
+void RenderWidgetHostViewAndroid::OnSetNeedsBeginFrame(bool enabled) {
+  if (enabled == needs_begin_frame_)
     return;
 
-  if (flush_input_requested_) {
-    flush_input_requested_ = false;
-    host_->FlushInput();
-    content_view_core_->RemoveBeginFrameSubscriber();
-  }
-
-  host_->Send(new ViewMsg_BeginFrame(host_->GetRoutingID(), args));
-}
-
-void RenderWidgetHostViewAndroid::OnSetNeedsBeginFrame(bool enabled) {
   TRACE_EVENT1("cc", "RenderWidgetHostViewAndroid::OnSetNeedsBeginFrame",
                "enabled", enabled);
-  // ContentViewCoreImpl handles multiple subscribers to the BeginFrame, so
-  // we have to make sure calls to ContentViewCoreImpl's
-  // {Add,Remove}BeginFrameSubscriber are balanced, even if
-  // RenderWidgetHostViewAndroid's may not be.
-  if (content_view_core_ && needs_begin_frame_ != enabled) {
-    if (enabled)
-      content_view_core_->AddBeginFrameSubscriber();
-    else
-      content_view_core_->RemoveBeginFrameSubscriber();
-    needs_begin_frame_ = enabled;
-  }
+  if (content_view_core_ && enabled)
+    content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
+
+  needs_begin_frame_ = enabled;
 }
 
 void RenderWidgetHostViewAndroid::OnStartContentIntent(
     const GURL& content_url) {
   if (content_view_core_)
     content_view_core_->StartContentIntent(content_url);
 }
 
 void RenderWidgetHostViewAndroid::OnSmartClipDataExtracted(
     const base::string16& result) {
@@ skipping 499 matching lines @@
 void RenderWidgetHostViewAndroid::RemoveLayers() {
   if (!content_view_core_)
     return;
   if (!layer_.get())
     return;
 
   content_view_core_->RemoveLayer(layer_);
   overscroll_effect_->Disable();
 }
 
+void RenderWidgetHostViewAndroid::SetNeedsAnimate() {
+  content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
+}
+
 bool RenderWidgetHostViewAndroid::Animate(base::TimeTicks frame_time) {
   return overscroll_effect_->Animate(frame_time);
 }
 
 void RenderWidgetHostViewAndroid::AcceleratedSurfacePostSubBuffer(
     const GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params& params,
     int gpu_host_id) {
   NOTREACHED();
 }
 
@@ skipping 91 matching lines @@
   if (compositor)
     return compositor->HandleInputEvent(input_event);
   return INPUT_EVENT_ACK_STATE_NOT_CONSUMED;
 }
 
 void RenderWidgetHostViewAndroid::OnSetNeedsFlushInput() {
   if (flush_input_requested_ || !content_view_core_)
     return;
   TRACE_EVENT0("input", "RenderWidgetHostViewAndroid::OnSetNeedsFlushInput");
   flush_input_requested_ = true;
-  content_view_core_->AddBeginFrameSubscriber();
 }
 
 void RenderWidgetHostViewAndroid::CreateBrowserAccessibilityManagerIfNeeded() {
   if (!host_ || host_->accessibility_mode() != AccessibilityModeComplete)
     return;
 
   if (!GetBrowserAccessibilityManager()) {
     base::android::ScopedJavaLocalRef<jobject> obj;
     if (content_view_core_)
       obj = content_view_core_->GetJavaObject();
@@ skipping 70 matching lines @@
 void RenderWidgetHostViewAndroid::SendKeyEvent(
     const NativeWebKeyboardEvent& event) {
   if (host_)
     host_->ForwardKeyboardEvent(event);
 }
 
 void RenderWidgetHostViewAndroid::SendTouchEvent(
     const blink::WebTouchEvent& event) {
   if (host_)
     host_->ForwardTouchEventWithLatencyInfo(event, CreateLatencyInfo(event));
+
+  // Send a proactive BeginFrame on the next vsync to reduce latency.
+  // This is good enough as long as the first touch event has Begin semantics
+  // and the actual scroll happens on the next vsync.
+  // TODO: Is this actually still needed?
+  if (content_view_core_) {
+    content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
+  }
 }
 
 void RenderWidgetHostViewAndroid::SendMouseEvent(
     const blink::WebMouseEvent& event) {
   if (host_)
     host_->ForwardMouseEvent(event);
 }
 
 void RenderWidgetHostViewAndroid::SendMouseWheelEvent(
     const blink::WebMouseWheelEvent& event) {
@@ skipping 46 matching lines @@
     if (content_view_core_)
       obj = content_view_core_->GetJavaObject();
     GetBrowserAccessibilityManager()->ToBrowserAccessibilityManagerAndroid()->
         SetContentViewCore(obj);
   }
 
   AttachLayers();
   if (content_view_core_ && !using_synchronous_compositor_) {
     content_view_core_->GetWindowAndroid()->AddObserver(this);
     observing_root_window_ = true;
+    if (needs_begin_frame_)
+      content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
   }
 
   if (resize && content_view_core_)
     WasResized();
 }
 
 void RenderWidgetHostViewAndroid::RunAckCallbacks() {
   while (!ack_callbacks_.empty()) {
     ack_callbacks_.front().Run();
     ack_callbacks_.pop();
@@ skipping 15 matching lines @@
   RunAckCallbacks();
 }
 
 void RenderWidgetHostViewAndroid::OnWillDestroyWindow() {
   // crbug.com/324341
   // WindowAndroid and Compositor should outlive all WebContents.
   NOTREACHED();
   observing_root_window_ = false;
 }
 
+void RenderWidgetHostViewAndroid::OnVSync(base::TimeTicks frame_time,
+                                          base::TimeDelta vsync_period) {
+  TRACE_EVENT0("cc", "RenderWidgetHostViewAndroid::OnVSync");
+  if (!host_)
+    return;
+
+  if (flush_input_requested_) {
+    flush_input_requested_ = false;
+    host_->FlushInput();
+  }
+
+  TRACE_EVENT0("cc", "RenderWidgetHostViewAndroid::SendBeginFrame");
+  base::TimeTicks display_time = frame_time + vsync_period;
+
+  // TODO(brianderson): Use adaptive draw-time estimation.
+  base::TimeDelta estimated_browser_composite_time =
+      base::TimeDelta::FromMicroseconds(
+          (1.0f * base::Time::kMicrosecondsPerSecond) / (3.0f * 60));
+
+  base::TimeTicks deadline = display_time - estimated_browser_composite_time;
+
+  host_->Send(new ViewMsg_BeginFrame(
+      host_->GetRoutingID(),
+      cc::BeginFrameArgs::Create(frame_time, deadline, vsync_period)));
+
+  // TODO(sievers): This should use the LayerTreeHostClient callback
+  bool needs_animate = Animate(frame_time);
+  if (needs_begin_frame_ || needs_animate)
+    content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
+}
+
 void RenderWidgetHostViewAndroid::OnLostResources() {
   ReleaseLocksOnSurface();
   if (layer_.get())
     DestroyDelegatedContent();
   DCHECK(ack_callbacks_.empty());
 }
 
 // static
 void
 RenderWidgetHostViewAndroid::PrepareTextureCopyOutputResultForDelegatedReadback(
@@ skipping 106 matching lines @@
 // RenderWidgetHostView, public:
 
 // static
 RenderWidgetHostView*
 RenderWidgetHostView::CreateViewForWidget(RenderWidgetHost* widget) {
   RenderWidgetHostImpl* rwhi = RenderWidgetHostImpl::From(widget);
   return new RenderWidgetHostViewAndroid(rwhi, NULL);
 }
 
 } // namespace content